Security documents, such as passports, usually comprise multiple pages which are bound together along one side, for example, by sewing sheets down the middle and then folding them at the sewing line whereby the fold edge becomes the bound side. One such page may be provided with an embedded contactless integrated circuit chip and antenna forming part of a security system designed to enhance the level of security associated with the document. Unlike other pages of the document made of paper, it is desirable that one page be made of a hard and durable synthetic material, such as a laminate of polycarbonate, which may be printed using a laser engraving process to provide greater security and/or may house an embedded circuit chip. However, unlike paper, a hard synthetic material sheet is unable to withstand stitching or folding during the binding of the document pages and this requires that it be incorporated into the security document by other means.
One such means is to affix the hard synthetic material sheet to a flexible band which can be effectively bound together with the other sheets of the security document. However, not all materials can be securely affixed to a hard synthetic material such as a polycarbonate laminate. Where like materials are selected for both the hard synthetic material sheet and flexible material layer, it is to be expected that they can be successfully laminated together to form a secure bond. An example of this is European Patent Application No. EP 1,245,407 of Setec Oy published on 27 Mar., 2002. However, the task of securely laminating or gluing together two dissimilar materials, such as a hard, polycarbonate material and a flexible material such as nylon, is problematic because instead of permanently bonding together they may be expected to fail to bond or to peel away from each other due to the incompatibility of the materials. For obvious reasons, any propensity for such impermanent bonding or peeling away between layers of the sheet materials is not acceptable for security document applications. Consequently, in order to couple a flexible material, of a type that can be sewn into a security booklet, to a hard laminate sheet it is desirable to have a durable and efficient method that allows direct coupling of those dissimilar materials in a permanent bond. In particular, it is desirable that a flexible material be used because of its advantageous properties for binding; however, a material such as nylon is unable to form a lamination bond with a polycarbonate sheet.
U.S. Pat. No. 6,213,702 to Wesselink, issued 10 Apr., 2001, discloses one solution to such problem posed by dissimilar materials, whereby a flexible band is affixed to a finished hard, synthetic sheet, referred to as a plate, by means of a separate joining strip positioned over the band. The joining strip is configured with projections to mechanically fit into mating perforations formed along the edge of the flexible band which is positioned over the hard sheet whereby the only direct connection made is between the joining strip and the plate, the connecting surfaces being the bottom surfaces of the projections and the top surfaces of the plate exposed by the perforations in the band. Those connecting surfaces of the separate joining strip and the plate are affixed by means of either a mechanical clamping fit between the projections and perforations or by fusing them together (i.e. by melting them together by ultrasonic welding if the material layer used for the joining strip is the same as that of the plate). However that possible solution has the disadvantage of requiring use of a separate joining strip.
European Patent No. 1,380,442 to Setec Oy, published on 14 Jan., 2004 discloses a security document comprising a durable data sheet with a more flexible band at one end for binding with additional sheets, whereby the data sheet is made up of several layers of which the inner layers are those which make up the flexible band and the outer layers are hard and durable. The data sheet is formed by laminating all of the layers together in the data area of those sheets but preventing lamination of the layers adjacent the flexible band by positioning upper and lower intermediary separation layers between them in only that end area. After lamination of the multiple layers together, the end layers above and below the separation layers are removed by cutting through the upper layers to the upper separation layer and cutting through the bottom layers to the lower separation layer. U.S. Pat. No. 6,135,503 to Lob et al. issued on 24 Oct., 2000 and PCT Published Application No. WO 2008/135285 to Giesecke & Devrient GmbH disclose similar methods employing a separation layer. Disadvantageously, however, these methods require the step of processing such intermediary separation layers in the area of the flexible band which are needed both to prevent lamination of the adjacent layers and to protect the flexible band from being damaged as a result of the cutting step.
U.S. Pat. No. 7,040,981 issued on 9 May, 2006 and assigned to the assignee of this application discloses a method for making a hard laminate sheet with an encased flexible band at one end which, advantageously, does not use a separation layer. A flexible band layer having a number of apertures formed in it, is provided as an intermediate layer at one end only of a laminate sheet, between laminate material layers, and the flexible material is made to overhang beyond the edges of the laminate material layers so as to form a flexible hinge component extending beyond the laminate sheet. In the remaining area adjacent to the flexible material layer, a laminate material layer is provided. Upon lamination of the sheet layers the adjacent laminate material layers bond together and, although the flexible band layer material does not bond to the adjacent laminate material layers, the laminate material layers which are adjacent to each other in the areas of the apertures formed in the flexible band layer do laminate and bond together within the areas of those apertures. These areas of bonded synthetic materials extend through the apertures of the flexible band layer and, thus, become encased within the laminate sheet. Advantageously, this serves to effectively secure the flexible band layer to the laminate sheet. The portion of the flexible band which overhangs the laminate sheet layers provides a flexible hinge that can be used to bind the laminate sheet within a security document. Disadvantageously, however, the need to overhang the flexible band component beyond the edges of the laminate sheet layers limits the production process to strips of two sheets only, so as to allow one overhang to extend along one edge of a laminating machine and the other overhang to extend along the opposite edge of the laminating machine. This limited processing ability results in less efficient production. Further, the multiple layer edges next to the flexible hinge, following lamination, are prone to inconsistent quality in the position, straightness and appearance of the edge as compared to the other edges of the laminate sheet which are cut.
Accordingly, there is a need for improvement over the inventions of the foregoing references in order to overcome the aforementioned disadvantages and provide improved manufacturing efficiency and options.